Diclofenac
An NSAID widely used in Pakistan, including by injection. Good for renal colic, but overused: it causes kidney injury and stomach bleeding.
Common brands in Pakistan: Voren. Brand availability changes; check with your pharmacy.
On this page
Uses
- Renal and biliary colic, musculoskeletal pain, gout, post-operative pain.
How it works
Diclofenac is a non-steroidal anti-inflammatory drug (NSAID). It blocks the cyclo-oxygenase enzymes (COX-1 and COX-2, with some preference for COX-2) that make prostaglandins, reducing pain and inflammation. Prostaglandins also protect the stomach lining and keep the afferent arterioles of the kidney open, which is why NSAIDs cause ulcers and kidney injury, especially in dehydrated patients. Its cardiovascular risk is higher than that of ibuprofen or naproxen.
When it is used
- Renal colic: an NSAID is the first-line painkiller, by any route. See renal colic.
- Biliary colic and musculoskeletal pain such as sprains and back pain.
- Acute gout and post-operative pain, usually with paracetamol.
- Not for: fever, dengue, patients with heart disease or kidney disease, or long-term pain when safer options exist. For regular NSAID use, ibuprofen or naproxen carry less cardiovascular risk.
Adult dose
| Route | Dose |
|---|---|
| IM | 75 mg once (occasionally twice daily for up to 2 days) |
| Rectal | 100 mg once daily (or 50 mg 2–3 times daily) |
| Oral | 50 mg 2–3 times daily with food |
| Maximum | 150 mg in 24 hours by all routes combined |
Kidney and liver
Avoid in kidney impairment and dehydration; a common cause of AKI in Pakistan.
Diclofenac can also raise liver enzymes; avoid in severe liver disease and check liver function with longer courses. See acute kidney injury.
Pregnancy and breastfeeding
Avoid in pregnancy.
From 20 weeks, NSAIDs can reduce fetal kidney function and amniotic fluid; in the third trimester they can close the ductus arteriosus early. Small amounts pass into breast milk; ibuprofen is usually preferred if an NSAID is needed while breastfeeding.
Side effects and cautions
- Stomach ulcers and bleeding.
- Heart attack and stroke risk: avoid in ischaemic heart disease, heart failure, stroke.
- Avoid in dengue, asthma triggered by NSAIDs.
- IM injections can cause abscesses and nerve injury; use oral or rectal routes where possible.
Contraindications
- Active peptic ulcer or a previous GI bleed or perforation with NSAIDs.
- Established ischaemic heart disease, peripheral arterial disease, cerebrovascular disease and heart failure.
- Severe kidney or liver impairment; third trimester of pregnancy.
- Previous asthma, urticaria or angioedema after an NSAID.
Other side effects
- Raised potassium, fluid retention and higher BP.
- Rarely, skin necrosis at the injection site; injection into the sciatic nerve causes foot drop.
Interactions
- ACE inhibitors or ARBs plus a diuretic: a well-known recipe for AKI. Avoid this combination, particularly in hot weather or with vomiting and diarrhoea.
- Anticoagulants, antiplatelets, SSRIs and steroids: more GI bleeding. Add a PPI or choose another painkiller.
- Lithium and methotrexate: levels rise. Ciclosporin: more kidney toxicity.
Monitoring
- Creatinine and potassium before starting in older patients, those with kidney disease or on the drugs above, and again within a few days.
- BP in hypertensive patients.
- Liver function and haemoglobin during longer courses.
Practical tips
- Rehydrate first. Many patients with renal colic have been vomiting; an NSAID on top of dehydration is how AKI starts.
- A 100 mg suppository works about as quickly as an injection for renal colic and avoids injection complications. Ask the patient's consent and explain how to insert it.
- If IM is chosen, give deep into the upper outer quadrant of the buttock or the lateral thigh, never into the lower or inner buttock.
- Ask what the patient has already had: repeated "pain injections" from local clinics before arriving at hospital are common in Pakistan and easily push the total above 150 mg.
- Add a PPI such as omeprazole if over 65, with a past ulcer or on aspirin, an anticoagulant or a steroid.
- Topical diclofenac gel is a sensible choice for localised sprains with much less systemic exposure.
- For FCPS revision, see analgesics and NSAIDs.
Frequently asked questions
What is the maximum dose of diclofenac?
150 mg in 24 hours, by all routes combined.
Is diclofenac injection safe?
It works well for renal colic but carries risks of kidney injury, bleeding and injection-site problems. Avoid in kidney disease, dehydration and heart disease.
Can diclofenac be given in dengue?
No. NSAIDs increase bleeding risk in dengue. Use paracetamol only.
Is a diclofenac suppository as good as an injection for kidney stone pain?
For most patients, yes. Rectal diclofenac acts quickly and avoids the abscess and nerve injury risks of IM injection.
Can diclofenac be taken with omeprazole?
Yes. A PPI protects the stomach and is recommended for patients at higher risk of ulcers. It does not protect the kidneys or heart.
Used in these guides
Sources
Doses on this page are typical doses from the sources above. Always confirm with a current drug reference, the product leaflet and your hospital protocol, especially in children, pregnancy and kidney or liver disease.
For FCPS Part 1
Revising for FCPS Part 1? Diclofenac is covered in our textbook chapter Analgesics and NSAIDs, with practice MCQs.